After losing my 47s ti Mini 123 at the Texas state fair last year I have a lanyard on every light going out the door, needless to say the replacement mini 123 has a lanyard on it and attached to my belt.
This is definitely not a stupid idea. Night canoeing/cayaking (especially when it wasn't done intentionaly) is one example of an activity that doesn't lend itself very well to a lanyard, especially if one light is needed for more than one person.
I haven't purchased one yet, but it should happen this week. Thanks for the product recommendation.